Systems that conduct pneumatic fluids have different valves for the monitoring and control of the pressure of those systems. For example, valves are used to adjust the pressure in a pneumatic system or in parts of a system of this kind, which regulate or reduce the pressure at the pressure input or output side thereof. Pressure relief valves are used in pneumatic systems of this kind to limit the pressure. The pressure relief valves may also have a fluid-conducting connection from a pressure line to a pressure accumulator. A pneumatic valve of this kind typically has a valve housing. The valve housing comprises at least a first media connection and a second media connection, which frequently form a media inlet port and a media outlet port. Often a piston valve element is guided in a guide in the valve housings of a pneumatic valve in an axially displaceable manner. A cross-sectional area of flow between the first media connection and the second media connection can be modified by an axial movement of the piston valve element, for example. Here, the piston valve element is preferably moved by an actuating device in one direction and by a reset device in the other direction. In this way, for example, the pressure at either one or the other media connections can be regulated and reduced.
DE 10 2009 010 339 A1 describes a proportional control valve for pneumatic applications, comprising a valve element that can be piezoelectrically activated, a sensor for measuring an actual value of a control variable, an electrical interface for receiving a control signal representing the target value for the control variable, as well as control electronics. The electrical interface is a 2-wire interface for receiving a pulse-width modulated, digital control signal. The proportional control valve is also configured to obtain the total electrical energy for operating the proportional control valve from the digital control signal.
The known pneumatic valves have electronically activated actuating devices, which are preferably activated in accordance with sensor signals of one or more valve-internal pressure sensors. In particular, the known proportional control valves are complex in structure, which complexity is associated with high manufacturing and assembly costs. The control electronics in particular have proven to be prone to frequent failure, in particular under “heavy operating conditions”.